A fluid controller to which the present invention is directed is called as a diaphragm valve and is used frequently (for example, refer to Patent Document 1=Japanese Unexamined Patent Publication No. 2003-42314). A typical structure thereof is shown in FIG. 4.
A fluid controller 1 comprises a block-like main body 2 having a fluid inflow passage 2a, a fluid outflow passage 2b and a concave portion 2c open upward, an annular valve seat 3 arranged in a peripheral edge of the fluid inflow passage 2a, a diaphragm 4 pressed against or moved apart from the annular valve seat 3 so as to open and close the fluid passage 2a, a valve body presser foot 5 pressing the diaphragm 4 and capable of moving in a vertical direction, a cylindrical hood 6 having a lower end portion inserted to the concave portion 2c of the main body 2 and extending upward, a tubular male thread member 7 screwed into a female thread portion formed in an inner periphery of the concave portion 2c of the main body 2 so as to fix the hood 6 to the main body 2, a cover 8 covering the hood 6 existing above the tubular male thread member 7, a valve rod 9 inserted into the hood 6 in a vertically movable manner, having a lower end portion brought into contact with the valve body presser foot 5 and having an upper end portion protruding upward from the cover 8, an opening/closing handle 10 fixed to the upper end portion of the valve rod 9 so as to be rotated, thereby moving the valve rod 9 in a vertical direction, and a compression coil spring 11 received between the lower end portion of the valve rod 9 and the upper end portion of the hood 6 and biasing the valve rod 9 downward.
The fluid inflow passage 2a of the main body 2 has one end which is open toward a left side and the other end which is open to a center portion of a bottom surface of the concave portion 2c. The fluid outflow passage 2b has one end which is open toward a right side and the other end which is open to a right portion of the bottom surface of the concave portion 2c. 
The cover 8 is formed into a cylindrical shape having a top wall 8a, and a through hole inserting an upper end portion of the valve rod 9 therethrough is provided in the top wall 8a. The handle 10 is formed into an approximately oval shape as seen from a plane, and is formed in a shape having a neck portion 10a in a center portion in a longitudinal direction. A countersunk head screw 12 passing through a peripheral wall of the cover 8 is screwed into a female thread provided in the hood 6, so that the cover 8 is fixed to the hood 6.
The valve rod 9 has a flange 9a in a lower end portion, and a lower end portion of the hood 6 is provided with an inner peripheral surface guiding the flange 9a in a vertically movable manner and a step portion inhibiting the flange 9a from moving above a predetermined position. A spring receiving ring 17 is attached to a portion above the flange 9a of the valve rod 9 via a bearing 16. The compression coil spring 11 is received by the spring receiving ring 17 and an annular step portion provided in an upper portion of the hood 6.
A gap is provided between the top wall of the cover 8 and the top surface of the hood 6, a horizontal shaft 13 is passed through the portion of the valve rod 9 positioned in this gap, and a bearing 14 is attached to each of both end portions. A guide surface 15 guiding the bearings 14 and formed into an annular shape as seen from a plane and into a smooth concavo-convex shape in a height direction is formed in an upper end of the hood 6. A pair of convex portions 15a existing at positions 180° apart from each other in the guide surface 15 support the bearing 14.
The valve rod 9 is always biased downward by a compression coil spring 11, and the bearing 14 is pressed against the guide surface 15 on the basis of a biasing force. The guide surface 15 gradually becomes lower in height in accordance with a movement in a circumferential direction from the convex portion 15a, and has a concave portion 15b having a lowest height at a position moved at 90° from the convex portion 15a in the circumferential direction. The figure shows a fluid path closed state. A pair of concave portions 15b in the guide surface 15 support the bearing 14. Accordingly, the valve rod 9 is positioned at a lower side, that is, a fluid passage closing position. Further, when the valve rod 9 becomes in a 90° rotated state from the state in the figure, the bearing 14 moves on the guide surface 15 in a state of being pressed against the guide surface 15 on the basis of the biasing force of the compression coil spring 11, and after being rotated at 90°, the pair of convex portions 15a in the guide surface 15 support the bearing 14. As a result, the valve rod 9 is positioned at an upper side, that is, a fluid passage opening position. Accordingly, the structure is made such that the handle 10 is rotated at 90°, so that a closed state and an open state can be switched.
In the conventional fluid controller 1 shown as one example in FIG. 4, an opening in a concave portion side of the fluid inflow passage 2a is faced to an inner side of the annular valve seat 3, and an opening in a concave portion side of the fluid outflow passage 2b is faced to an outer side of the annular valve seat 3, a maximum value (about one third of a diaphragm diameter) of each of the diameters of the openings are limited by the diaphragm diameter (a diameter of the concave portion). In order to increase a flow rate coefficient or a Cv value, it is necessary to increase the diameter of the opening in the concave portion side of each of the passages 2a and 2b, that is, the diameter of the diaphragm 4. Accordingly, it is necessary to make a size of the fluid controller 1 large. However, in the existing device, there are many cases that the fluid controller can not be increased in size due to a problem of an installation space, and it is hard to make the flow rate large.
An object of the present invention is to provide a fluid controller which can circulate a large flow rate of fluid without enlarging its size.